Shale gas mining technology realizes localization

China Petrochemical Corporation announced on December 29, 2015 that as of the end of 2015, the national shale gas demonstration zone in the Fuling Mountain area of ​​Chongqing has successfully achieved the goal of building an annual production capacity of 5 billion cubic meters, which means commercialization in China. Shale gas development has entered the second place in the world, second only to the United States.

The Fuling Mountain area in the upper reaches of the Yangtze River is currently the largest shale gas field in China. Looking down from the sky, the rigs are like red stars dotted in the Bishan Gorge on the banks of the Liling River. In November 2012, the first shale gas wells drilled by Chinese oil and gas workers were successfully vented, and the raging fire that ignited ignited China’s confidence in shale gas mining. This well became a “shale qigong” well. ".

Today, more than 223 shale gas wells have been mined in the Fuling Mountain area of ​​more than 220 square kilometers. At present, 174 wells have been providing clean energy to central and eastern China through the Sichuan-East Gas Pipeline.

Behind the breakthrough in capacity, the shale gas mining technology has basically achieved the whole process of localization. According to Sinopec Jianghan Petroleum Engineering Co., Ltd., 24 national patent inventions have been obtained in the technology, process and equipment of shale gas development. All key technologies and core equipments have broken the monopoly of foreign technology.

Shale gas is an unconventional natural gas that was first discovered in 1821 and was first discovered in the United States in 1921. China has the world's largest shale gas reserves, with a recoverable resource of about 26 trillion cubic meters, and its resource potential is similar to that of the United States.

The biggest difference between shale gas and conventional natural gas is that the way and state of underground storage are different. The shale gas is attached to the shale. Therefore, it is impossible to extract gas by mining conventional natural gas. There is a saying in the industry: The shale gas revolution is actually a mining technology revolution.

“If you compare conventional natural gas to blood collection in veins, then developing shale gas is like taking blood directly from the capillaries,” said Zhang Liangwan, director of the Southwest Project Management Department of Sinopec Jianghan Petroleum Engineering Company and shale gas technology expert.

It is understood that shale gas is different in storage mode and mining technical requirements are different. Horizontal wells and staged fracturing are the most critical technologies in shale gas development and are the most difficult technology. A horizontal well is equivalent to drilling a horizontal "tunnel" into the shale gas under the ground. Conventional oil and gas development is mostly a shaft, and shale gas needs to open a horizontal “horizontal well” because it is mainly adsorbed in the underground mud shale layer. "First vertical and then horizontal, turning is difficult, the direction of the angular position can not be wrong." Zhang Liangwan said.

After several optimizations of the drilling process, the attack team of Jianghan Oilfield Petroleum Engineering Company also invented the “well factory” drilling operation mode, and the construction time was reduced by an average of 20 days. In the past, oil and gas exploitation was to drill a well and then disassemble the rig. Through the ground supporting equipment and three-dimensional technology application, the “well factory” realized the mobile drilling without derrick, and the efficiency increased by 30%.

How to make the gas wells collect the natural gas stored in the “capillaries” into the wells, which requires a key technology “pressure” in the mining, that is, the formation of the horizontal wells is about 300 meters. Crush so that the gas collects into the well. In the underground of several kilometers, it is a difficult technical work to keep the wellbore intact so that it can be smoothly vented, and to smash the surrounding rock formation. Fracturing equipment and methods are the core technology for shale gas mining.

Sinopec Jianghan Petroleum Engineering Company and Siji Factory and other units collaborated to tackle the problem, developed large-scale fracturing equipment with independent innovation, broke the foreign technology blockade, and some key equipments also succeeded in “reverse attack” and became export stars, such as key technology segmentation fracturing. "Bridge plug."

"In the past, we needed to use the bridge plug of the United States. Now our independent research and development of the bridge plug has been innovative. Last year, we exported 6,000 sets to North America," said He Kaiping, party secretary of Sinopec Jianghan Petroleum Engineering Company.

At present, the total amount of shale gas that can be mined in China is similar to that of the United States, but the US shale gas has accounted for 35% of its total natural gas production. China's current shale gas production is less than 1% of natural gas production, and there is huge room for development.

On September 24, 2015, the Ministry of Land and Resources announced that the proven reserves of the Fuling shale gas field were 273.484 billion cubic meters. According to estimates, by 2017, the capacity of the Fuling shale gas field will reach 10 billion cubic meters. In terms of environmental protection, it can reduce carbon dioxide emissions by 12 million tons per year, equivalent to 8 million economic cars to stop for one year.